A brief review of radiation hormesis

Abstract

This paper reviews physical, experimental and epidemiological evidence for and against radiation hormesis and discusses implications with regards to radiation protection. The scientific community is still divided on the premise of radiation hormesis, with new literature published on a regular basis. The International Commission on Radiological Protection (ICRP) recommends the use of the Linear No Threshold (LNT) model, for planning radiation protection. This model states that the probability of induced cancer and hereditary effects increases with dose in a linear fashion. As a consequence, all radiation exposures must be justified and have a sufficient protection standard in place so that exposures are kept below certain dose limitations. The LNT model has sufficient evidence at high doses but has been extrapolated in a linear fashion to low dose regions with much less scientific evidence. Much experimentation has suggested discrepancies of this extrapolation at low doses. The hypothesis of radiation hormesis suggests low dose radiation is beneficial to the irradiated cell and organism. There is definite standing ground for the hormesis hypothesis both evolutionarily and biophysically, but experimental evidence is yet to change official policies on this matter. Application of the LNT model has important radiation protection and general human health ramifications, and thus it is important that the matter be resolved.

Low-dose Radiation Induces Antitumor Effects and Erythrocyte System Hormesis

“…Some researchers (Pandey & Rizvi, 2011) reported that the enhancement of immune function could persist for several weeks under single or chronic irradiation. Other researches (Jolly & Meyer, 2009) showed that single fraction irradiation could enhance immune function, this reaction would last for 7 days, but not more than 14 days. Our study showed erythrocyte immune function was still excited 15 days after whole body low dose radiation by 7.5cGy single fraction irradiation.…”

Initial Characterization of the Growth Stimulation and Heat-Shock-Induced Adaptive Response in Developing Lake Whitefish Embryos after Ionizing Radiation Exposure

“…Multiple cellular and molecular events have been implicated in the hormetic response, including the upregulation of stress response proteins, DNA repair mechanisms, bystander effects and free radical scavenging (34). Specifically, growth stimulation after irradiation has been correlated with an activation of cell proliferation signaling pathways (28,35,36).…”

Low Dose Radiation Exposure and Cardiovascular Diseases: A Review

“…The LNT model shows satisfactory evidence at high doses; however for low doses, a linear fashion has less scientific evidence. Applications of the LNT model and radiation hormesis have an important effect on radiation protection and general human health [3]. Causes of Cardiovascular Diseases CVD is the leading cause of death and disability in elderly people.…”